The invention relates to a hydraulic camshaft adjuster and to a method of assembling the same for a camshaft of an internal combustion engine, comprising an inner body, which is connected to the camshaft in a rotationally fixed manner and has outwardly extending blades and an outer body, which is mounted rotatably relative to the camshaft and has blades extending inwardly between the outwardly extending blades so as to form at least one hydraulic medium chamber between two opposite cover plates, a driving connection from a crankshaft to the outer body, and with a locking device which locks the inner body in relation to the outer body with at least one bolt, which is movably disposed in the inner body for engagement in a locking cavity in one of the two covers, which are connected to the outer body.
In order to reduce the fuel consumption and the emissions and to increase power and torque, spark-ignition engines are generally equipped with camshaft adjusters. The latter change the phase position of the camshaft relative to the crankshaft. Currently, hydraulic blade-type adjusters with working chambers are generally used. The adjustment is undertaken by the controlled admission of oil from the engine circuit via a control valve into the chambers formed between adjacent blades. The control valve is operated by an electromagnetic control device.
DE 102 53 496 A1 discloses a camshaft adjuster of the generic type and is intended for adjusting the angle of rotation of the camshaft in relation to a crankshaft of an internal combustion engine. The camshaft adjuster has an outer body which is connected in a rotationally fixed manner to a drive wheel and an inner body which is connected in a rotationally fixed manner to the camshaft, the outer body having at least one hydraulic chamber and the inner body having at least one rotor blade which divides the hydraulic chamber into two working chambers. The rotor blade can be moved hydraulically between a late stop and an early stop by means of a controlled oil pressure. One of the stops forms the base position in which the blade can be locked by means of a spring-loaded locking pin which can be released hydraulically and which is moved into a locking groove or bore for locking purposes. The locking pin prevents an undesired movement of the camshaft adjuster if no oil pressure is present. These locking pins have a locking play in the locking grooves caused by the sum of the tolerances, some play being necessary for reliable functioning of the lock. The locking play should be large enough such that reliable locking and release operation can be obtained, but small enough to avoid the generation of noise. The generation of noise results from the undamped striking contact of a rotor blade and early stop or late stop, on the one hand, and the locking pin entering the locking groove, on the other hand. The aim of obtaining a quiet engine and a reliably operating lock can generally only be achieved by means of an exacting tolerance of the locking play. However, this exacting tolerance not only has technological limits for adjusting the locking play but moreover monitoring this adjusting operation by continuously measuring the locking play is very costly.
It is the principle object of the present invention to provide a hydraulic camshaft adjuster and a method for assembling the same in such a manner that reliable assembling of the camshaft adjuster with minimal locking play and without an adjusting process is possible.